The objectives of this project is to observe patterns of human physiology throughout 24 hours. We do this firstly, in order to investigate the occurrence and relevance of the postulated "basic rest-activity cycle" (BRAC) and secondly, to identify and investigate abnormalities in the phase, amplitude, frequency, or association (i.e., free-running) of ultradian and circadian rhythms in human illness. Special methods to include CNS monitoring, continuous bood withdrawal, and novel urin and plasma hormone assay procedures. Data is being obtaind by sleep recordings, body temperature, tapping tests, Stanford sleepiness scale; time estimation; serum growth hormone; serum and urinary cortisol; and urinary volume, electrolytes and creatinine. Assay of other hormones will follow in year 2. Present investigations include: (1) Normal and narcoleptc males (overnight or 24 hours . (2) The "90-minute day" protocol - alternating sleep (30 minutes and wakeflness (60 minutes) for 5-1/3 solar days. Includes 28 hour continuous blood withdrawal. (3) 48 hour rest/activity protocol. Includes 48 hour continuous blood withdrawal. (4) Pilot study of "programmed" sleep arousal. (5) 36-day investigation of blind subject suspected to be symptomatically "free-running" in normal society. (6) Partial construction of novel data acquisition system.